Radiation-shield.



E. W. KELLY.

RADIATION SHIELD.

APPucATmN FILED Nova la. 1912.

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RADIATION SHIELD.

APPLICATION FILED NOV.18, 1912. 1,156,906. Patented 00u19; 1915.

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To all whom t may concern. v `\Be it known that I, EDWIN W. KELLY, a

'UNITED sTATEs PATENT OFFICE.

c i EDWIlIN W. KELLY, F PHILADELPHIA, PENNSYLVANIA. i

` aAmATmNsHIELD.

.'icitizen ofthe United States, residing .in the city of Philadelphia,countyof Philadelphia,

"and State of Pennsylvania, have inventedk ,certain new and usefulImprovements in :Radiation-Shields, of which thev following `is aspecification. F

It is the object of my invention to provide'means for shielding anoperator from harmful radiations, such as X-rays. To this Aend I providea box or inclosure for the V.source of radiations, such as an X-raytube,

which is provided with lead or lother ray `'absorptive material gradedor varied as to fits thickness, and therefore as to absorptive power,according to the locality of the absorptive' material with respect tothe source. vof radiations, this being, in the case of an -1 X-ray tube,the focus spot onthetarget.

yBy my invention I am enabled to protect` :ran operator from the primaryradiations,

y as well as secondary, tertiary and other radiations with relativelysmall amount of ray yapparatus is both cheapened and lightened weight.

absorptive materialwith the result that the For an illustration of oneof the forms my invention may'take reference is to be had to theaccompanying drawings, in which:

Figure 1 is a vertical sectional view through a shield box and its rayabsorptive l'material, some parts shown in elevation. IFig-2 is afragmentary front elevational l'view l of the apparatus shown inFig.v 1. Fig. 3 is a horizontal. sectional view, taken -on the lines A-Aof Fig'.v 1.

. "The X-ray tube X is supported by any suitable means within the boxBofwood or any other suitable material. L The X-ray tube comprises theusualtarget or vanode a and cathode la, and vacum regulator 1'.

As vvwell understood in connection with X-rays these rays existsubstantially entirely in a. hemisphere bounded by a plane embracing andcoincident with the lplane of the face of target a, such planebeing'fl'jepresented by a dotted line p,- Fig. 1. The rays in thishemisphere are substantially all primar or direct raysI and are theeffective rays for are at the same time the most harmful to theoperator.

The front of the box B has an aperture b and' registering with thisaperture b is-the4 aperture' c in the plate or casting C of lead ISpecification of Letters Patent.

`-ray operations or investigations and or terial.

.The thickness of the plate or casting C is a maximum where it isnearest the focus spot f on the anode or target a and diminishes inthickness in all directions, upwardly, downwardly, and laterally asindicated in Figs. 1, 2 and 3. The thickness at all points is howeversufficient toibsorb `practically'all the primary rays impining upon theinside of the plate or casting and all secondary or tertiary rays thatmay impinge upon it. The thickness of the plate C at any point isa'function'of 'the distance of that point from focus spot f. The plateor casting C is secured to the any`other suitable ray absorptive mafrontof the box or support B by any suit- ,able means such as screws '1, 1Fig. 2. At its top and at the centermay be provided a lu y 2 assuitablemeansfor grasping the plate erably of lead, attached tothesebars' 8; and J9. As to the operation ofv the'shutter lor diaphragmit will be noted that each of the pivoted bars carries one-diaphragmelement and that as the parallelograms are flattened "these membersapproach each other. v And Patented Oct. 19, 1915. Application filedNovember 18, 1912. Serial No. 732,055.

similarly the laterally disposed lugs 12 and -13 are provided upon theplate C, and .upon

these lugs are pivoted bars 14 and 15 pivoted I attheir outer ends tothe bars -l'and 17,

constituting a p'arallelogram motion for moving'the diaphragm members 10and llat-` tached to the bars V16 and 17 respectively. The bar 17 has anextension 2,0 and thebar 8 hasan extension 21 by which these paral-L 100 `lelogram motions may be actuated to move the diaphragm members toadjust the extent of aperture between for purposes of more or less'restricting the fieldof the X-rays,

passing from the target a through the aperture c to the object underinvestigation.

On each side of the box B is provided a plate or casting D, of lead orother suitable y ray absorptive material. The upper edges of theseplates D slant downwardlyv and back- Wardly from the front of the box asindiv cated by the dotted line in Fig. l, such edge v beingsubstantially parallel With the plane of the target a'bt some distanceback of or bove the plane of the target a shown in ".lhe plate C on thefront of the box'extends upwardly beyond the plane of the tar-4 get a,asindicated in Fig. 1. -Above the plate C is ay relatively thin plate E,cf lead or other suitable absorptive material applied to the box B andextending over its top as shown in Fig. l, and on the sides above platesD. In this region Well back of the plane of the target a and in what may'be called the inactive hemisphere, there practically are no directradiations, but only secondary or tertiary radiations, Which arecompletely absorbed by the thin sheet metal E. Qn the bottom of the boxB, as shown in ig. 1, is provided a sheet of metal F, of lead or othersuitable ray absorptive material Which is preferably thicker than thesheet metal E because the plate F is Within the active hemisphere, butof such substantially uniform distance from the focus spot f that littleor no economy Would be effected by changing its thickness with thevariations in distance of its parts from the spot 7".

'lhe plate C has flanges 22 embracing the edges of the plate D, clearlyshown in section in Fig. 3, and as these plates D are of varyingthickness, (as explained, these flanges 22 extend from varying Widths ofthe plate C as indicated in Fig. 2. The box B may be provided with aremovable or hinged cover Cr4 carrying the blocks of Wood or othermaterial 23 through which extend;

the rubber or other insulating rods 24, 25 and 26 inclosing theconductors 27, 28 and 29 respectively, which connect With the positiveterminal 30, the vacuum regulator terminal 31 and the-negative terminal32 of the X-ray tube X.

Vand sides of the cover G, Within the active hemisphere, is a sheet J oflead or other ray absorptive material, of greater thickness y than thesheet H because disposed Within the active hemisphere. In the sheets Hand J are provided apertures 33 and 34 around the rods 24, 25 and 26,these apertures being large enough to prevent the short circuiting,

of the high tension current from the conductors 27 and 29 to each otherthrough the metallic sheeting. Due to these apertures however there is apossibility of escaping from .Within the box of some of the rays.

rlhrough the aperture 34 there Would escape some direct or primary raysWere it not for the fact that there is disposed in the path of such raysabsorptive material such as the? sheets of lead glass 35 and 36 carriedby the block 23 and of such size and so positioned as to prevent raysescapin through the aperture 34 through the Woo 23 and the cover G. Theaperture 33 is in the inactive hemisphere Where the radiations are farweaker and in this case a single sheet of lead glass 37 is supportedupon the upper block 23 of such dimensions and in such position as toprevent rays escaping through the aperture 33. For the sheets of leadglass 35, 36 and 37 other ray absorptive material may be employed as,for example, sheets of lead.

It Will be noted that the absorptive material of varying thickness,varies in thickness in a direction of a rectilinear ray from the focusspot f With distance from such focus spot, and simultaneously varies inthickness in a directionnormal to the surface of the support, as theflat outer surface of the box B.

From the foregoing description it is apxparent that 1 have 'providedmeans for shielding against primary, secondary, tertiary and lesserradiations by th`e employment of a relatively smally amount of rayabsorptive material With resulting cheapening and lightening of Weightof the ray absorptive materialand of the apparatus as a Whole; thelightening of Weight being of further importance because of frequentneed for moving the X-raytube and its shield as a unit.

What I claim is. y

l. The combination With an X-ray tube, of .a shield inclosing the sameand comprising a mass of ray absorptive material varying in thicknessbetween its inner and outer faces With distance from the focus spot of'said tube and varying in thicknessv in a radial direction from saidfocusspot With distance from said focus spot'. i

2. r1he combination With. an X-ray tube,

. of a shield support having a surface varying in distance from thefocus spot of said tube, a shield comprising ray absorptive materialdisposed upon said surface, said ray absorptive material having'different thicknesses `measured normally to said surface and differentthiclmesses measured radially from the focus spot of said tube.

3. The combination with an X-ray tube, of a shield support having asurface vary- Aing in distance from the focus spot of said said memberhaving an aperture member having a substantially dat surface,

a shield of ray absorptive material disposed upon said surface, said rayabsorptive material diminishing in thickness normally to said'surfaceand radially from the focus spot of said tube with increasing distancesfrom the focus spot of said tube.

5. The combination with an X-ray tube, ofv a shield therefor comprisinga' support, ray absorptive material having an aperture in front of thefocus spot of said tube, said ray absorptive material diminishing inthickness in a direction away from said aperture, asheet of rayabsorptive material on said support in the active hemisphere in front ofthe focus spot, and a sheet of ray absorptive material of differentthickness 0 and the ray-absorptive material back of on said support backof said focus spot.

6. The combination with an X-ray tube,"- .of a box inclosing the same, asheet of conductive ray absorptive material disposed upon a wall of saidbox, said sheet having apertures conductors extending to the terminalsof said tube through said apertures and spaced in said aperturesfromsaid material, and lray -absorptive material interposed between saidapertures and said tube. .7. The combination with an X-ray tube, of aconductor communicating with a terminal thereof, ray'absorptive materialhaving an aperture through which said conductor passes, and rayabsorptive material intervening between said aperture and said X-raytube.

8. The combination with an X-rayv tube, of a substantially at shieldmember of ray absorptive material associated therewith, through whichdirect rays may be passed, said member diminishing in thickness in avdirection. away'from said aperture, and a diaphragm of ray absorptivematerial supported on said member.

9. The combination with an X-ray tube, of a box inclosing the' same, acoating of ray absor tive materlal on the walls' of said box,thetickness-of said ray absorptive material diminishing with thedistance of said material from the focus spot of said tube.

focus spot to the plane bounding said hemisphere.

1'1. The combination with an X-ray tube, of a shield therefor comprisingra -absorptive `mat erial inclosing said tube and disposed at varyingdistances from the focus spot thereof, said ray-absorptivematerialwithin the active hemisphere diminishing in thickness from the regionnearest said focus spot to the plane bounding said hemisphere,

said plane being relatively thin and of substantially uniform thickness.

12. The combination with anX-ray tube,

of a box and its -cover, ray-absorptive material inclosing said tubecarried by the' walls of said box, said walls being substantially flat,and said ray-absorptive material diminishing in thickness from theregion nearest the focus spot of said tube to the plane bounding theactive hemisphere.

13. The combination with an X-ray tube, of a box having front and sidesinclosing said tube, the walls of said box being substantially dat, rayabsorptive material dis-l posed upon the front and sides of said box,the ray absorptive material infront of sald box diminishing in thicknesswith distance from the focus spot of said tube, masses of ray absorptivematerial on the sides of .sald box and having edes slantingsubstantlally `parallel Awiththe ace of the target of ysaid tube, saidlast named masses diminishing in thickness with distance from the focusspot of said tube.

In testimony whereof I have hereunto aixed my signature in the twosubscribing witnesses.

' EDWIN W. KELLY.

Witnesses:

E. T. MGCALL, NELLIE EVANS.

presence of the

